Slowing down Cheynne

[mjrhealth 3]

Love it but its like a squirrel on coffee, dosnt want to slow down, have to reduce power untill speed drops below gear down speed, lower gear which slows it down a little more, first flap position, then slow power adjustments to keep speed, above blue line, once on glide slope, let nose fall then trim for approx 500fpm GS and seems to go ok but does speed up, so constantly watching speed. Being doing touch and goes and slowly improving but must get a yoke or better joystick. Any suggetions on slowing down. ??

[Shaun Fletcher 570]

Hello mjrhealth,

Is this thread here of any interest to you.

[Aerosoft Team [Inactive Account] 51558]

Hello mjrhealth,

Is this thread here of any interest to you.

And it is a turbo prop those engines can't really run slow, so you need to use the prop levers to reduce thrust. The airframe is also very slippery.

[pbearsailor 9]

On your initial slowdown from cruise, it's really hard to go down and slow down at the same time--you need to level off, and pull the power all the way back if you want (it's a turbine engine and doesn't care about shock cooling like a piston does).

A normal real world descent in something like this is to start down from FL200 at 60 miles, coming down at 2000 fpm or so and maintaining power to keep the speed close to redline (always get the people where they want to go as quickly as you can, hehe). Assuming an ILS approach, you don't really worry about slowing until you're cleared down to initial approach alititude. Just want to make sure you get to approach flaps and gear by the outer marker and personally, I'd be hanging full flaps at 500' agl, only when I'm sure I won't have a go around.

You can hang out one notch of flaps at 171 KIAS, so that's the first step, and gear at 154 (both numbers for the Cheyenne I). Once you get dirtied up with approach flaps and gear, it should be fairly easy to manage speed and descent.

I'm finding my normal approach at 120 kts or around blue line I'm using a power setting that just barely has the ignition lights coming on in the annunciator panel. There is some lag in a PT6 engine, so you have to be ahead of it in terms of power changes.

Like SAF pointed you to in that link, if you overtorque it, the power tends to hang at full for a long time, making it really hard to set. Gotta stay below the red torque limit.

Hope that helps.

cheers,

steve

[pbearsailor 9]

use the prop levers to reduce thrust

Actually, no. We'd leave prop levers set for cruise RPM all the way to touchdown and the copillot would push the prop levers up at touchdown as the left seater goes into reverse. If you pull the power back to idle, she'll slow down just fine, just got to plan for it.

A little trick on descent planning. Take your cruise altitude in thousands and multiply it by 3. FL200 is 20 x 3 = 60 miles out is where you want to start your descent for a sea level airport. You can keep doing the math in your head on the way down to maintain a proper descent profile, increasing or decreasing rate of descent to match the formula. Like, passing through 10,000 feet, you should be 30 miles out. Do that and you won't wind up too high and too fast, as that can be embarassing as the pax will wonder why you are circling to get down.

cheers,

steve

[Aerosoft Team [Inactive Account] 51558]

Actually, no. We'd leave prop levers set for cruise RPM all the way to touchdown and the copillot would push the prop levers up at touchdown as the left seater goes into reverse. If you pull the power back to idle, she'll slow down just fine, just got to plan for it.

A little trick on descent planning. Take your cruise altitude in thousands and multiply it by 3. FL200 is 20 x 3 = 60 miles out is where you want to start your descent for a sea level airport. You can keep doing the math in your head on the way down to maintain a proper descent profile, increasing or decreasing rate of descent to match the formula. Like, passing through 10,000 feet, you should be 30 miles out. Do that and you won't wind up too high and too fast, as that can be embarassing as the pax will wonder why you are circling to get down.

cheers,

steve

I stand corrected!

[pbearsailor 9]

cheers m8!!

[mjrhealth 3]

Thanks guys all appreciated and i was wondering what those two lights that flicked on and off with low torque where, now i know, so i wasnt far off.

[Ken Stallings 1]

What Steve writes is very true, and not only in a turboprop!

In any aircraft it is a very bad combination to be fast and high trying to plan an approach to land. And the best way to slow down is to pull the power and remain level and wait for the speed to bleed down to the target speed you want. Then, you configure with gear and flaps for the approach and let the nose down to maintain your desired approach airspeed.

Ken

[Ken Stallings 1]

I stand corrected!

Mathjis,

I don't think Steve is trying to say that it's improper to apply full RPM for the descent to land. It does increase low power drag slightly, so it can help. In fact, in some aircraft the checklist directs the pilot to apply full RPM as part of the before landing checklist.

What Steve is saying is that the pilot can elect to avoid doing this since with the reduced drag he is saving some fuel. And fuel is money!

Cheers,

Ken

[mjrhealth 3]

Yes in the DSH8 300 when slowing down to land you can hear the prop RPM wind up and plane slows quiet quickly. Oh and holding the nose up whilst reducing power is usually how I do it.

David